Thanks for the replies, y'all!
If I were starting from scratch I would be willing to get tanks with installed overflows for sumps, but my existing tanks don't have them and I don't want to drill them, nor do I want siphon overflows which have the same drawbacks in my scenario as HOBs (take up too much space behind tank, visually disruptive). A common sump is no-go, the tanks will not be near one another. I appreciate the thought, but I have thought through the alternatives and I am set on canisters.
I hadn't heard of the Odyssea filter, thanks for bringing it to my attention!